This is not just any turkey dinner, this is school turkey dinner - the new, tasty perfectly balanced version.

The kids love it and experts, who have worked hard at making sure it does not contain too much salt, sugar, fat and calories, hope it will help win the battle against obesity.

As the new school term starts, every one of the 17,500 primary schools must serve the new meals.

And it got the thumbs up from the children the Mirror chatted to at Sunnymede primary in Billericay, Essex. Oscar Taylor, 10, said: "The roast dinner is my favourite.

"It's brilliant. I love the potatoes and the carrots." And even though it costs just £1.75, the portions are generous too. Oscar tucked into three slices of turkey with two large roasties and veg.

Head Karen Cooke said it is what the children want.

"We spoke to the children and asked them what they liked. We looked at their favourites and saw what we could give them."

Scientists say children need 14 nutrients to stay healthy and have calculated exactly how much of each essential elements including vitamins, calcium, zinc, protein, carbs, folate and fibre are required.

A healthy balance will not only keep them slim - a quarter of five year-olds are overweight - but helps prevent heart disease, skin and eyesight problems and arthritis.

School secretary Sue Farrow is the brains behind the catering operation at Sunnymede. She spent hours getting to grips with IT software which calculates how much of everything every meal contains.

That means shortbread is off the menu in favour of fruit jelly moving the fortnight's calorie count safely to green.

Sue has 1,621 dishes to choose over two weeks so if one choice has too much or little of a particular thing then that is balanced out another day.

She said: "The computer automatically calculates how much of everything the children are getting over the two-week menu cycle. It can take a lot of tinkering to make sure you get everything right but we can more or less give them what we want."

The numbers of pupils eating school dinners slumped after TV's Jamie's Dinners. But that is changing with 43 per cent of primary school kids opting for a cooked meal compared to 41 per cent a year ago.

Secondary schools will have to bring in the new style meals by September next year.

School Food Trust Chairman Prue Leith said: "This week we begin the final steps in radically changing school food. Overfatty, salty, or sugary are gone, replaced by nutritious and delicious meals."

Back at Sunnymede, the children are wolfing down their dinners. As well as the turkey and potatoes, there's broccoli, carrots, freshly baked wholemeal bread and fruit salad. Georgia Cullum, eight, said: "My favourite is the roast dinner. The potatoes are just really nice. I love the carrots too and like to have them at home."

There is beef lasagne and chicken casserole with rice on the menu for the rest of the week.

But the roast dinner is definitely the kids' top choice. Lily Jae, eight, said: "I really like the dinner. Everything about it tastes really nice and it always fills me up."

Pupils will have to stay on at school until they are 17 under Government plans. The 11-year-olds going into year seven this week will be the first affected by raising the school leaving age to 17 by 2013 and then 18 by 2015.

They will not have to study Alevels. Teenagers can now take diploma courses in engineering, construction, IT, media and health. Eventually 17 diploma courses, combining study with work experience will be available.

What must go into pupil's ideal dinner

Maximum:

530 calories

70.6g of carbs

15.5g of certain sugars

20.6g fat

6.5g saturated fats

499mg of salt

Minimum:

7.5g protein

4.2g fibre

10.5mg vit C

193mg calcium

3mg iron

2.5mg zinc

Also levels for vit A and folate

43% OF PRIMARY PUPILS TOOK SCHOOL DINNERS LAST YEAR, UP FROM 41% THE YEAR BEFORE